The present invention relates generally to the field of radio-frequency identification tags including, but not limited to, radio frequency identification tags having a printable display.
Radio frequency identification tags and radio frequency identification tag systems are known, and find numerous uses. For example, radio frequency identification tags are frequently used for personal identification in automated gate sentry applications protecting secured buildings or areas. Information stored on the radio frequency identification tag identifies the person seeking access to the secured building. Older systems require the person accessing the building to insert or swipe a programmed identification tag into or through a reader for the system to read the information from the identification tag. A radio frequency identification tag conveniently reads the information from the radio frequency identification tag at a small distance using radio frequency (RF) data transmission technology eliminating the inserting or swiping operation. Most typically, the user simply holds or places the radio frequency identification tag near a base station, which is coupled to a security system securing the building or area. The base station transmits an excitation signal to the radio frequency identification tag that powers circuitry contained on the radio frequency identification tag. The circuitry, responsive to the excitation signal, communicates the stored information from the radio frequency identification tag to the base station, which receives and decodes the information. The read information is communicated to the security system and, if appropriate, access is granted to the individual. In general, radio frequency identification tags are capable of retaining and, in operation, transmitting a substantial amount of informationxe2x80x94sufficient information to uniquely identify individuals, packages, inventory and the like.
A typical technology for powering and reading a radio frequency identification tag is inductive coupling or a combination of inductive power coupling and capacitive data coupling. Inductive coupling requires incorporating a coil element into the radio frequency identification tag. The coil element is excited (or xe2x80x9cenergizedxe2x80x9d) by an excitation signal from a base station to provide power to the radio frequency identification tag circuitry. The radio frequency identification tag coil, or a second tag coil, may be used to transmit and receive the stored information between the radio frequency identification tag and the base station. Inductive coupling technology is relatively expensive, particularly for applications where it may be desirable to have a disposable radio frequency identification tag such as in an inventory management application. Radio frequency identification tags relying on inductive coupling are also sensitive to orientation of the radio frequency identification tag with respect to the base station since the field created by the excitation signal must intersect the coil element at substantially a right angle for effective coupling. Furthermore, read ranges for inductively coupled devices are generally on the order of several centimeters. Longer read distances are desirable, and for certain applications, such as electronic animal identification, baggage tracking, parcel tracking and inventory management applications, are necessary.
The radio frequency identification tag systems and radio frequency identification tags disclosed in the above cross-referenced applications provide for substantially increased read/write distances over those available in the prior art. An advantage derived from the use of the systems and tags therein disclosed is that the user need not bring the radio frequency identification tag in close proximity to a base station or to substantially orient the tag with respect to the base station. It is therefore possible to incorporate the antenna elements of the base station into, for example, a doorway or a vestibule and to energize the tag and read the tag information at a greater distance. A user passing through the doorway need not be concerned with moving the radio frequency identification tag into close proximity to the base station.
In some systems, the base station is arranged to include a visual or audio alert, or potentially both alert types, to allow the user to know that a successful reading and/or writing of the tag information has occurred. With the advent of the above-described improvements in read/write distances the tag is no longer brought into close proximity with the base station. Hence, the user""s attention is not drawn to the base station such that an alert co-located therewith is not effective for signally the user that a read/write operation has transpired. Moreover, antennae associated with the base station may be integrated into the structure of the doorway or vestibule and the actual base station electronics may be remotely located therefrom.
It has been suggested to provide a visual alert, in the form of a display, as part of the radio frequency identification tag. The task is much easier said than done. Display devices typically have high power consumption, and a remotely powered radio frequency identification tags operate under substantial power constraints. Additionally, it is the goal to make the components of the radio frequency identification tag as small as possible with a completed tag, for example, being no larger than a typical credit card. Display devices tend to be rather large. Still, with remote location of base station components and substantially increased read distances, it is desirable to integrate a display or other visual alert into the radio frequency identification tag to assist the user in its operation.
Thus, there is a need for an improved radio frequency identification tag.